Data items in the PDBX_VALIDATE_CHIRAL category list the
residues that contain unexpected configuration of chiral
IMPROPER HA N C CB chirality CA
IMPROPER HB1 HB2 CA CG stereo CB
as this number approaches (+) or (-) 180.0, then the
error in predicting the true chirality of the center increases.
Improper dihedrals are a measure of the chirality/planarity of the
structure at a specific atom. Values around -35 or +35 are expected
for chiral atoms, and values around 0 for planar atoms.
HERE improper C---N----CA---CB done
expected answer is around -120 mean -122.52
D-amino acid is +120.0